Absorption Coefficients exceeding a value of 1?

z60611 · Post by **z60611** » Wed Jun 07, 2006 6:12 am

Ethan

How thick is the metal

0.7 mm

what type?

Steel

Were the panels flat on the floor or raised up?

On the floor.

If raised, by how much?

They were on the floor, so 0.

What do the percent numbers along the left edge mean?

The change in sabins between having them together and apart.

Did you measure at many different spacings or just one spacing in addition to the panels adjacent?

There were 13 tests performed not counting the empty room test.
But for the purposes of that chart above, just the two measurements are compared.

Why does the disparity peak at 200 Hz rather than falling off linearly as you'd expect?

I don't know.

What are "baffles with metal center core?" Is this not plain rigid fiberglass or mineral wool?

The aborbers (aka baffles) are 32kg/m^3 polyester 65mm thick with a 35 mm air cavity behind them, enclosed in a five sided steel box, leaving only one surface of the polyester exposed (the top).

When was this test done?

In or before 2003

In what lab?

The Reverberation lab of the Catholic University of Leuven

And by whom? You?

Eric and Professor Dr. Lr. Gerrit Vermeir.

Measurements included T10, T20, T30 from 80hz to 6300hz. The T30 is the most useful of these. The report includes the times for the empty room, and the calculations for Sabin values as a result of adding the treatments under test.

Eric_Desart · Post by **Eric_Desart** » Wed Jun 07, 2006 6:27 am

z60611 wrote:
Did you measure at many different spacings or just one spacing in addition to the panels adjacent?
There were 13 tests performed not counting the empty room test.

I only showed 13.

z60611 wrote:
What are "baffles with metal center core?" Is this not plain rigid fiberglass or mineral wool?
The aborbers (aka baffles) are 32kg/m^3 polyester 65mm thick with a 35 mm air cavity behind them, enclosed in a five sided steel box, leaving only one surface of the polyester exposed (the top).

?????????????????????

Ethan Winer · Post by **Ethan Winer** » Wed Jun 07, 2006 6:28 am

Bob,

Thanks!

Do we know why Eric couldn't say that for himself?

Also, that data would be much more compelling if it included identical tests where the same panels were not enclosed in the steel cases. Especially since the metal is so thin it's not much more than foil.

--Ethan

Eric_Desart · Post by **Eric_Desart** » Wed Jun 07, 2006 6:30 am

You know this thread is linked elsewhere now he? Let's play innocent again.

This thread was about YOUR info, and this is discussed before.

There's nothing foil about that frame, you even have no idea how it is made.
Expected diversion starts. Again another escape route.

Thanks Bob. I'll try for another 3 years to protect people against misinformation.

z60611 · Post by **z60611** » Wed Jun 07, 2006 6:45 am

Eric:

z60611 wrote:
Quote:
What are "baffles with metal center core?" Is this not plain rigid fiberglass or mineral wool?
The aborbers (aka baffles) are 32kg/m^3 polyester 65mm thick with a 35 mm air cavity behind them, enclosed in a five sided steel box, leaving only one surface of the polyester exposed (the top).
?????????????????????

That was my interpretation of what the word document said.
In the header of the chart on page 2. The headers are
"Polyester 32kg/m^3 - 65mm + air cavity 35mm (Tot 100mm)"
"Empty Reference Reverberation Room"
"Sabine & Stand Dev"

What were the baffles?
(not that it makes any difference for the purpose of the chart is trying to explain -- you could be measuring with dead mice in a boxes and that would be fine too)

Eric_Desart · Post by **Eric_Desart** » Wed Jun 07, 2006 6:48 am

z60611 wrote:Eric:

z60611 wrote:
Quote:
What are "baffles with metal center core?" Is this not plain rigid fiberglass or mineral wool?
The aborbers (aka baffles) are 32kg/m^3 polyester 65mm thick with a 35 mm air cavity behind them, enclosed in a five sided steel box, leaving only one surface of the polyester exposed (the top).
?????????????????????
That was my interpretation of what the word document said.
In the header of the chart on page 2. The headers are
"Polyester 32kg/m^3 - 65mm + air cavity 35mm (Tot 100mm)"
"Empty Reference Reverberation Room"
"Sabine & Stand Dev"

What were the baffles?
(not that it makes any difference for the purpose of the chart is trying to explain -- you could be measuring with dead mice in a boxes and that would be fine too)

BOB I REFUSE TO GO INTO THOSE BAFFELS HERE. Whatever you read here is not related to those absorbers. This description does not fit.
And this has nothing to do with what the measurements I entered represent. I described exactly what they stand for.
This is just an escape route from the hart of this thread.

z60611 · Post by **z60611** » Wed Jun 07, 2006 6:51 am

powerjoe · Post by **powerjoe** » Wed Jun 07, 2006 3:19 pm

In deference to the true acoustical scientist (Eric Desart) on this thread, I have deleted this and another post. By chance, Ethan Winer is right for once; my contribution to THIS thread did not help the argument.

However, I still expect that weekly letter from ETHAN WINER'S attorney.

Sorry for any incovenience, please continue.

Joel DuBay

Ethan Winer · Post by **Ethan Winer** » Thu Jun 08, 2006 12:34 am

Just so it's perfectly clear, our friend powerjoe is none other than Joel DuBay, who fancies himself a competitor to my company. Since Joel has nothing technical to contribute to this discussion, and certainly doesn't have a better product, I guess he feels this is the only way he can compete. Wow, both of you guys are pathetic. I think it's time for Steve or John to lock up this puppy. Way to go guys. Yet another potentially interesting technical discussion flushed down the toilet.

BTW Joel, I plan to "out" you at AVS very soon. I'm just waiting for the ideal opportunity.

--Ethan

Eric_Desart · Post by **Eric_Desart** » Thu Jun 08, 2006 1:35 am

Ethan Winer wrote:Just so it's perfectly clear, our friend powerjoe is none other than Joel DuBay, who fancies himself a competitor to my company. Since Joel has nothing technical to contribute to this discussion, and certainly doesn't have a better product, I guess he feels this is the only way he can compete. Wow, both of you guys are pathetic. I think it's time for Steve or John to lock up this puppy. Way to go guys. Yet another potentially interesting technical discussion flushed down the toilet.

BTW Joel, I plan to "out" you at AVS very soon. I'm just waiting for the ideal opportunity.

--Ethan

Methaphorical:

Please .........
Steve ............... John ....................
Lock it .......................... please ..................

Then it looks that others are responsible for:

Ethan Winer wrote:Yet another potentially interesting technical discussion flushed down the toilet

And I, Ethan Winer, can hide behind someone/something else ......
I don't like responsibility for my own actions ...., hate it ......

This stupid pathetic Eric, forces me to stay on topic, prevents me to divert and diffuse stuff. I'm not use to that ...., I'm used I can wrap guys.....
I write what I see fit, I make it look like science, and it supports my goals ....

And this pathetic Joel, thinking he means something, I'll deal with him in my own manner. I'll just "out" him first chance I get.

If you please ??????

End Methaphorical

Not methaphorical:
Thanks for being more transparent

A quote from an Academic who publically states he does like you:

Terry Montlick http://www.avsforum.com/avs-vb/showthread.php?p=7767755&&#post7767755 wrote: <snip> Many of us on the forum with better science backgrounds have tried to teach him things in the past, with only very limited success. We tend to get frustrated, and have largely given up trying. When he posts incorrect information as acoustical fact, it is pretty much useless to argue, at least on the basis of science.

I like Ethan. He is a nice guy. <snip>

Ethan Winer · Post by **Ethan Winer** » Thu Jun 08, 2006 2:39 am

Anyway, as I was saying...

The main reason you can get absorption coefficients larger than 1.0 is when the edges of a panel are exposed - the total absorbing surface is increased but not accounted for when converting Sabins to absorption coefficients.

If diffraction occurs at the edges of a panel that is a totally separate issue, and is certainly unrelated to simply having more total surface area. If diffraction alone really could account for a big increase in measured absortion, we wouldn't have to use fiberglass at all! We'd just make panels from sheet steel.

Another way to get more than 1.0 is by spacing a panel off the wall or hung a few inches below the ceiling. This lets the rear absorb as well as the sides, and this type of mounting is a big feature of RealTraps products. The air gap also increases bass absorption, so it's a win-win all around.

--Ethan